Pre heating and Tesla charger

[kevin ellard]

I drove to Leeds and back in the last few days and thought I'd give the Tesla charger at Trumpington (Cambridge) a go. On the way up I only seemed to get 30-35 kW on the way back down I thought I'd give the battery pre-heating a try and put it on 30 mins before the stop and charged at 70-75kW almost straight away. I don't rapid charge often but I'll try and remember to pre-heat in future.
Interestingly, "battery heating while driving" is remembered when you turn it off and back on again. I can think of a lot of other setting that would be more useful for me if it remembered them.

 

[MickeySw]

…don’t forget pre-heating only seems to work when battery cell temperature is below 10 deg although that also depends on (BMS?) FW version…

 

[kevin ellard]

Is there any way to see the battery temperature?

 

[MickeySw]

Is there any was to see the battery temperature?

Yes, via OBD dongle and app (Car Scanner or eZS).

Another quick way to figure at what ambient temperature the heater kicks in is to select the voltage/amp/rpm screen and watch the current value when activating the heater in standstill (Ready).

It’s meant to be a 3kw heater therefore you should see around 7-8A (@400V)

 

[Coulomb]

Battery temperature is one I'd like to see on the voltages and currents page.

Are you listening MG? Oh wait... ?

 

[Gomev]

Battery temperature is one I'd like to see on the voltages and currents page.

Are you listening MG? Oh wait... ?

MG did listen to a lot of feedback from the original ZS EV after it was launched in the UK. Members of this forum posted a lot about their wants etc. and this was fed back to MG via one of our esteemed members Miles of Chorley MG.
A great deal of the suggestions were acted upon as updates and then built in to the facelifted models.
I'm sure some of our longer term residents here will remember this such as @Lovemyev

 

[Lovemyev]

MG did listen to a lot of feedback from the original ZS EV after it was launched in the UK. Members of this forum posted a lot about their wants etc. and this was fed back to MG via one of our esteemed members Miles of Chorley MG.
A great deal of the suggestions were acted upon as updates and then built in to the facelifted models.
I'm sure some of our longer term residents here will remember this such as @Lovemyev

Yes - I remember it clearly @Gomev.
I think Miles sat down with a few of the early members and they ended up with three sides of an A4 sheet of recommendations for MG to look at.
Some of these were implemented on the face lift model, but some features from the “wish list” unfortunately could not be included due to cost, or time restrictions in order to hit the build slot at the factory I guess.

 

[Manuscrit81]

Hello to all of you Gentlemens. I am part of a French Forum covering MG5 topics similarly to this one. According to the numerous feedback from the guys, we have concluded that the pre-heating system from MG5 is under-powered (3kW only whereas a good 5/6kW shall be necessary to be efficient in winter). An alternative to "artificially" increase the Temperature is to "play" with the regenerative braking half hour before charging (by oscillating +/- 20km/h in the highway. It is technically not so complicated to oscillate this way and ODB dongle monitoring show good temperature increase (thus optimizing the charging time).
Last but not least, the latest MCU version R17 do not improve the pre-heating system efficiency (numerous feedback evidenced by ODB monitoring).

 

[MickeySw]

Hello to all of you Gentlemens. I am part of a French Forum covering MG5 topics similarly to this one. According to the numerous feedback from the guys, we have concluded that the pre-heating system from MG5 is under-powered (3kW only whereas a good 5/6kW shall be necessary to be efficient in winter). An alternative to "artificially" increase the Temperature is to "play" with the regenerative braking half hour before charging (by oscillating +/- 20km/h in the highway. It is technically not so complicated to oscillate this way and ODB dongle monitoring show good temperature increase (thus optimizing the charging time).
Last but not least, the latest MCU version R17 do not improve the pre-heating system efficiency (numerous feedback evidenced by ODB monitoring).

Ye seem to have done a lot more OBD data analysis, do you know what factor wind chill plays on battery temperatures, i.e does a 2h motorway trip @ 70miles/h in winter heat the batteries sufficiently for fast DC charging?

 

[Manuscrit81]

At 70 miles/h (110-115km/h) stabilized speed, the battery barely heats up. At 80mi/h (130km/h), it heats up a little faster. However, the internal resistance of LFPs is ridiculously low, but at these speeds the joule losses in the battery are still counted in thousands of watts.
On the other hand, the thermal management system is poorly optimized: by default the cooling circuit runs constantly and it is permanently connected to the car's radiator! So if it's cold outside, the battery stays cool :-( Unless the battery drops below 10 degrees, the radiator is shunted. But the damage is done, and the next recharge will be very slow.

 

[MickeySw]

At 70 miles/h (110-115km/h) stabilized speed, the battery barely heats up. At 80m/h (130km/h), it heats up a little faster. However, the internal resistance of LFPs is ridiculously low, but at these speeds the joule losses in the battery are still counted in thousands of watts.
On the other hand, the thermal management sytem is poorly optimized: by default the cooling circuit runs constantly and it is permanently connected to the car's radiator! So if it's cold outside, the battery stays cool :-( Unless the battery drops below 10 degrees, the radiator is shunted. But the damage is done, and the next recharge will be very slow.

Thanks for the info, that basically means no amount of winter driving will heat the cells sufficiently for fast charge rates, but it could warm them just enough (around 10deg) that the manual battery heating doesn’t kick in..

Can you elaborate a bit more on the ‘regen brake’ heating hack?

 

[Manuscrit81]

To answer your question @MickeySw , I better directly quote the obervations from a member of the French MG5 Forum (source: Link to Source).
His obervations are based on practical test on road+ data monitoring via ODB Dongle.
I also used Google translate. Hope the translation will be as faithfull as possible.

Quote
I did a little test today to see if the R17 update changes anything, I wasn't expecting a change and there wasn't one...
Here a screenshot of the car scanner graph over 30 minutes with battery temperatures.
I activated the battery heating from the start, but the battery was above 10 degrees so nothing happened.
LFPs have remarkably low internal resistance, and running at 80 km/h doesn't heat it up at all.
You can see that the temperature started to rise when I started accelerating and braking to warm the battery --> (Note: Here is the famous 'regen brake' heating hack). It's quite effective and in around twenty minutes the maximum temperature rose by 6 degrees and the minimum temperature by 3.5 degrees.

Arriving at the terminal with 22%, once plugged in the car started to heat up the battery; it was charging at 38kW, then the power slowly dropped to 35kW, and as soon as the minimum temperature exceeded 15 degrees it reset to the nominal power and the heating stopped (at 45% it took ~ 55kW).
End

 

[MickeySw]

To answer your question @MickeySw , I better directly quote the obervations from a member of the French MG5 Forum (source: Link to Source).
His obervations are based on practical test on road+ data monitoring via ODB Dongle.
I also used Google translate. Hope the translation will be as faithfull as possible.

Quote
I did a little test today to see if the R17 update changes anything, I wasn't expecting a change and there wasn't one...
Here a screenshot of the car scanner graph over 30 minutes with battery temperatures.
I activated the battery heating from the start, but the battery was above 10 degrees so nothing happened.
LFPs have remarkably low internal resistance, and running at 80 km/h doesn't heat it up at all.
You can see that the temperature started to rise when I started accelerating and braking to warm the battery --> (Note: Here is the famous 'regen brake' heating hack). It's quite effective and in around twenty minutes the maximum temperature rose by 6 degrees and the minimum temperature by 3.5 degrees.

Arriving at the terminal with 22%, once plugged in the car started to heat up the battery; it was charging at 38kW, then the power slowly dropped to 35kW, and as soon as the minimum temperature exceeded 15 degrees it reset to the nominal power and the heating stopped (at 45% it took ~ 55kW).
End

Cheers for the references (top marks for google translate). I might be wrong but LFP packs seem to be still in the minority (e.g not available on MG5 in Ireland).
But the same principles apply to NMC chemistry although DC charging rates seem significantly higher…